With rapid growth of information technology electronic equipments also become very popular. Take the commonly used computers as example, they can be grouped to desktop computers, notebook computers and tablet computers. To increase computer document processing speed most computers are incorporated with a keyboard to facilitate data entry operation of users. The keyboard generally has keycaps and a baseboard. Each keycap and the baseboard are bridged by a key strut. When the keycap is stricken by a user the key strut supports the keycap to form vertical movement against the baseboard. Thus, when the keycap is pressed a switch on the baseboard can be triggered to transmit a reference signal to the processor to output a desired output signal. In addition, to avoid the keycap from being stricken by the user at two sides rather than in the center and result in tilting and unstable, or unable to trigger the switch, a high sensitive keyboard has been developed in the industry to enable the user to strike the key even on corners and still can trigger the switch.
For instance, Taiwan patent No. 1346965 discloses a high sensitive key structure. It mainly provides a plurality of protruding units on outer sides of a keycap and a plurality of suspending arm units on a baseboard. When a user presses the edges of the keycap the protruding units touch the suspending arm units to make the free end of suspending arm units to set on a circuit switch via the lever principle. Hence even if the key is being pressed unevenly the circuit switch still can be activated, thus can achieve high sensitivity.
In addition, Taiwan patent No. 1396218 also proposes a keyboard which mainly has a plurality of trigger portions on a keycap and a plurality of switches on a thin film circuit board corresponding to the trigger portions. A user can press merely any corner of the keycap to touch and set on a switch to output a signal, therefore can improve the sensitivity of the keycap.
The aforesaid keyboards use an elastic support rack to support the keycap, then through a press point protruding sideward from the elastic support rack to touch a switch on a circuit board that is located on a corresponding press point. Furthermore, all the aforesaid keyboards include an elastic support rack. The press point of the keycap generates a relative swing about the elastic support rack as a fulcrum. However, the elastic support rack makes shrinking the size of the keyboard difficult. Moreover, user has to forcefully press the keycap to deform the elastic support rack to make the press point to touch the switch. If the user lightly touches the corners of the keycap set-on connection could fail. All this shows that to design a high sensitivity multipoint contact keyboard that also is thin and light still is an issue pending to be resolved.